Used in microbiological assays to determine the concentration of folic acid in pharmaceuticals and biological samples. Supports the growth of microorganisms like Lactobacillus casei, which require folic acid for growth, allowing quantification based on turbidity or growth rate. Commonly applied in quality control of vitamin supplements, fortified foods, and raw material testing in the pharmaceutical industry. Also utilized in research settings to assess folic acid bioavailability and metabolism.